1. Field of the Invention
This invention relates to a composite comprising one or more substantially interwoven matrix compositions each containing a refractory hard metal. More particularly, this invention relates to a densified composite comprising one or more substantially interwoven matrix compositions each comprising a refractory hard metal and a metal compound, which may optionally also contain one or more densification materials; and methods of forming such composites.
2. Description of the Prior Art
Refractory hard metals, such as TiB.sub.2 or ZrB.sub.2 are useful in applications where a material is needed possessing chemical inertness and/or mechanical strength, particularly at elevated temperatures. Such uses include dies for drawing, forming, or extruding; adiabatic engine components; abrasive disks or wheels; structural components; tool bits: or as electrodes, e.g., a cathode, in an electrolytic reduction cell for the production of metal, such as aluminum.
The use of ceramic materials in applications requiring resistance to high temperature, corrosion conditions, and high wear conditions is not new. For example, the use of laminated layers of two or more ceramic materials to form refractory tubes is described in Milligan et al U.S. Pat. No. 2,640,503; Venable U.S. Pat. No. 3,714,971; and Dancy et al U.S. Pat. No. 4,082,863. Ceramic materials have also been impregnated or dispersed in other ceramic materials to improve the characteristics of the resulting product. For example, Kaneko et al U.S. Pat. No. 3,919,755 describes a ceramic liner for an automobile exhaust system comprising a material such as alumina or silica impregnated with a suitable heat-resistant such as sodium silicate or colloidal silica and Moore et al U.S. Pat. No. 3,284,144 teaches forming a gas-lubricated bearing using discrete alpha alumina crystals in a glassy matrix such as a silica glass containing alumina and magnesia.
Bearings with ceramic liners have been proposed in British Pat. No. 1,389,410; while Tucker U.S. Pat. No. 3,941,903 teaches the use of a wear-resistant hard phase bearing material such as a metal oxide, metal carbide, metal boride, metal nitride or metal silicide, e.g., alumina, titanium boride, zirconium boride, etc., uniformly dispersed in a soft ductile metal matrix.
Combinations of ceramic and metal layers have also been used such as metal pipes with ceramic liners by Sowards U.S. Pat. No. 3,568,723; and in the production of ceramic lined cylinder walls for internal combustion engines by Kistler Re. U.S. Pat. No. 23,976. Metal gun barrels with ceramic liners are described by Whitlow U.S. Pat. No. 3,523,035; Thomsen U.S. Pat. No. 3,742,640; and Claussen et al U.S. Pat. No. 4,401,729.
In my parent U.S. patent application Ser. No. 604,913, there is disclosed a novel composition in which a refractory hard metal, such as TiB.sub.2, is formed in a substantially interwoven matrix with a metal compound by a displacement reaction. This invention relates to a densified composite which includes one or more of such substantially interwoven matrix compositions and the method of making such composites.